Major Histocompatibility Complex

What is the Major Histocompatibility Cmplex?

complex of genes that encode molecules on the cell surface

True or False: Antigen fragment/epitope must fit the MHC molecule

TRUE

True or false: Antigen fragment/epitope must fit the antigen receptor

True

Costimulation

a system of checks and balances where more than one signal is required to elicit an efficient immune response

Genetic polymorphism

variants or alternative forms of a gene present in a population at a stable frequency

Allele

one type of variant

Homozygous

having two identical alleles of the same gene

Heterozygous

having two distinct alleles of the same gene

Haplotype

the collective set of MHC alleles present in an individual genotype

polymorphic

large number of alleles for each gene

polygenic

there are many different MHC genes

Class I molecules are found on:

all nucleated cells

.  Class II molecules are found on:

antigen presenting cells

Class II loci codes for receptors for:

exogenous or extracellular antigens

Class II loci codes for receptors for:

endeogenous or internal antigens

True or False: The rearrangement and number of loci varies among species and even breeds.

TRUE

What does MHC III code for?

protiens involved in innate and adaptive immunity, apoptosis, protection from cellular damage and apoptosis,

MHC I molecules can be upregulated by what?

Type 1 interferon (IFN-a or b)

True or False: MHC genes are expressed codominately

TRUE

What is the advanateg of heterozygosity?

ability to recognize a arge number of peptides

Steps of Class I processing

1. intracellular proteins are broken down by the proteasome

2. fragments are transported from the cytolasm to the ER by a transporter associated with antign procesing (TAP)

3. MHC I assembled in the ER

4. complex is transported to the cell surface

5. complex acts as a ligand for cytotoxic T cells

Steps of Class II processing

1. Extracellular antigens are taken in via endocyosis via endosomes

2. MHC II ae synthesized in he ER

3. MHC II is transported from the ER to the golgi apparatus to endosomes where antigen processing occurs, then the fragment is loaded onto the class II molecule in the endosome

4. complex is transported to the cell surface for helper T cells

MHC restriction

only molecules that can bind in the grove of a MHC molecule will trigger and immune response

True or False: In any given outbred population, there will be a range of responses from a few reacting very strongly to a few reacting very weakly, with the majority of the population reacting moderately.

TRUE